The present disclosure relates to an apparatus for regulating an output voltage and an apparatus for boosting a voltage.
A touchscreen pad is a device enabling a user to input data by simply touching a screen with her/his finger or another object. To date, such a touchscreen pad has been typically used in industrial or manufacturing facilities. As such touchscreen pads have evolved to have greater responsiveness and multi-touch capabilities, these devices have come into common use in relatively small devices such as mobile phones and display devices.
Further, as touchscreen pad technology is rapidly advancing, electronic devices such as laptop computers, mobile phones and smartphones are increasingly being provided with touch panels, in place of traditional data input devices such as keyboards and computer mice. Touch panels may be divided into capacitive touch panels and resistive touch panels, and recently, the former have been more commonly employed.
Capacitive touch panel determine the position of a touch by detecting changes in capacitance occurring in capacitors when touched by a finger. Unfortunately, capacitive touch panels have a drawback in that a signal to noise ratio (SNR) may be reduced due to external noise (power noise, LCD noise and the like) as the size of a touch panel is increased, and thus a touch may not be readily recognized. To overcome this, a method of boosting a voltage by using a charge pump so that the panels are robust against noise is commonly used. A charge pump has characteristics in which an output voltage therefrom varies according to a load current, and the output voltage from the charge pump may be increased due to external factors or the like.
Patent Document 1 below discloses a charge pump circuit able to obtain a desired output voltage without exceeding withstanding voltages of integrated circuits or the like by controlling levels of charges accumulated in a charge accumulation capacitor. However, Patent Document 1 fails to disclose the feature of regulating the output voltage from a charge pump by way of reducing the output voltage if it is sensed that the output voltage from the charge pump becomes higher, as will be discussed in the present disclosure.